Numerous processes have been proposed for the removal of sulphur oxides from industrial offgases. Most such processes provide for desulphurization of the gases with subsequent discharge of the gases via a stack. To ensure sufficient lift in and above the stack, the gases must have a temperature of at least 200.degree. C after desulphurization.
A drawback of processes in which the sulphur oxides are absorbed in a solvent is that the non-absorbed gases must be heated after desulphurization. It has therefore been proposed to pass the gases containing the sulphur oxides at higher temperatures over acceptors on which the sulphur oxides are accepted. The gases then give up their sulphur oxides at a temperature desirable for the stack and the offgases can be discharged directly.
In some processes, the acceptor loaded with sulphur oxides is not regenerated, and in other processes it is. In the latter case, the acceptor can be used again for accepting sulphur oxides.
The present invention relates to the latter type of process, and particularly to a process in which the loaded acceptor is regenerated with a reducing gas. In the regeneration of the loaded acceptor, the process produces a regeneration offgas containing, besides converted and unconverted compounds from the reducing gas, also sulphur compounds. Depending on the conditions chosen for the process, such as reducing capacity of the reducing gas, the regeneration offgas will contain SO.sub.2, SO.sub.3, H.sub.2 S, COS, CS.sub.2 and similar sulphur compounds in various proportions.
These sulphur compounds must be rendered harmless, and they are usually converted into elemental sulphur. However, this conversion is expensive and laborious, particularly when the concentration of sulphur compounds in the regeneration offgas is not high. Another problem is that the regeneration offgas still contains a quantity of reducing components that cannot easily be utilized.
The present invention aims at obviating these drawbacks.